XPS and SPS Studies on Nanometer Au/TiO_2 Photocatalyst
JING Liqiang 1,2 , LI Xiaoqian 2, LI Shudan 1, WANG Baiqi 2, XIN Baifu 1, FU Honggang 1* , WANG Dejun 3, CAI Weimin 2(1 Laboratory of Physical Chemistry, School of Chemistry and Material Sciences, Heilongjiang University, Harbin 150080, Heilongjiang, China;2 Department of Environmental Sciences and Engineering, Harbin Institute of Technology, Harbin 150001, Heilongjiang, China; 3 School of Chemistry, Jilin University, Changchun 130021, Jilin, China)
Au/TiO 2 samples were prepared by impregnation of TiO 2 nanoparticles prepared by sol-gel process with HAuCl 4 solution. The samples were characterized by X-ray photoelectron spectroscopy (XPS) and surface photovoltage spectroscopy (SPS) techniques. The effects of calcination temperature and Au content on the photocatalytic activity of TiO 2 nanoparticles for phenol degradation were investigated. The results showed that Au was uniformly dispersed on the surface of TiO 2 nanoparticles as metal nanocrystallite. The surface modification with appropriate content of Au not only made TiO 2 samples expand the response range of light, but also enhanced the separation efficiency of photoinduced electrons and holes, increased the adsorption of oxygen species and promoted the transfer of photoinduced electrons to the adsorbed oxygen species. During the photocatalytic oxidation of phenol, Au/TiO 2 calcined at 500 ℃ displayed higher activity, which was in agreement with the XPS and SPS results. The mechanism of Au modification effect on the surface photoelectric properties and photocatalytic performance of TiO 2 samples was discussed from the electron energy level point of view.